問86
頻出度★★☆
職場のLANにPCを接続する。ネットワーク設定情報に基づいてPCにIPアドレスを設定する方法のうち, 適切なものはどれか。 〔ネットワーク設定情報〕 ・ネットワークアドレス 192.168.1.0 ・サブネットマスク 255.255.255.0 ・デフォルトゲートウェイ 192.168.1.1 ・DNSサーバのIPアドレス 192.168.1.5 ・PCは, DHCPサーバを使用すること
平成23年度 特別試験 ITパスポート試験 問86
テクノロジ系ネットワーク › 通信プロトコル
This question's explanation and your answers so far.
解説
問 86
Incorrectア
192.168.1.0 is the network address (the address whose host part is all zeros under the subnet mask 255.255.255.0). It is a special address that represents the network itself, so it cannot be assigned to an individual PC. It also goes against the instruction to use DHCP.
Incorrectイ
As shown in the configuration information, 192.168.1.1 is already used as the address of the default gateway (the router). Setting the same address on the PC causes a duplicate IP address, so communication becomes impossible. This also goes against the instruction to use DHCP.
Incorrectウ
192.168.1.150 is within the range of host addresses usable on this network and also satisfies the condition of being currently unused, but this is a way of setting the IP address manually (statically). It does not follow the instruction in the configuration information that the PC must use a DHCP server. In addition, if that address is included in the range distributed by the DHCP server, the same address may later be handed out to another device, causing a duplicate address.
- エ
正解 The last line of the configuration information specifies that the PC must use a DHCP server. DHCP (Dynamic Host Configuration Protocol) is a mechanism in which a server automatically distributes an IP address, a subnet mask, a default gateway, a DNS server address, and so on to a PC when it connects to the network. Therefore, what should be set on the PC is not typing in each value by hand, but configuring it to obtain an IP address automatically (that is, making it run as a DHCP client). With this setting, an IP address matching the given 192.168.1.0/24 network, together with the default gateway 192.168.1.1 and the DNS server 192.168.1.5, is assigned all at once by the DHCP server, and there is no risk of conflicting with the administrator settings. Therefore エ is appropriate.
ここがポイント
- DHCP is a mechanism by which a server automatically distributes an IP address, a subnet mask, a default gateway, a DNS server address, and so on. In an environment that uses DHCP, all that is needed on the PC side is to configure it to obtain an IP address automatically.
- Some addresses must not be assigned to hosts. The network address whose host part is all zeros (for example, 192.168.1.0) and an address already in use by another device (for example, the default gateway 192.168.1.1) cannot be set on a PC.
用語